Medical officials are warning people to be careful and remember the danger heat can bring as temperatures have begun climbing into the 90s in many parts of the state.

Lara O'Leary, spokeswoman for the Emergency Medical Services Authority, said Friday paramedics responded to two heat-related calls this week.

A heat alert is issued when EMSA responds to five or more heat calls in a 24-hour period.

“EMSA advises everyone to take the increasing temperatures very seriously and follow the basic guidelines of hydration, limited heat and sun exposure, and pay attention to heat exhaustion signs to avoid EMSA treatment this summer,” O'Leary said.

At least 21 people died in Oklahoma last year during the worst heat wave in state history.

The state set a record in July for highest average monthly temperature recorded anywhere in U.S. history. Highs were in triple digits for most of the summer, with little relief at night.